How do I rearrange the list of render layers?
Render layer order doesn't actually effect the render (aside from maybe changing the order in which the layers are rendered). 

However, for organisational purposes it can be nice to reorder them. For this reason I created a script, available on Github, which adds up and down arrows to reorder the render layers:

https://github.com/RayMairlot/Move-Render-Layers

Note: Untested in the latest version of blender, not guaranteed to work, save before using etc.